Some machines, for example an excavator, include an aft structural section often referred to as a boom. The aft structural section or boom can include a boom foot section connected to the upper frame of the machine, a boom center section and a boom nose section which provides a pinned attachment to an arm which is connected to a bucket or other tool. The boom foot is typically connected to the upper frame of the machine by a boom foot pin that passes through a boom foot casting or forging. The boom foot transmits boom loads to the upper frame of the machine. The transition from a tall box section of the boom (between the boom foot and center sections) to the boom foot pin connection to the upper frame occurs over a very short distance. During corner digging and side loading of the bucket, large torsional loads exist at a boom joint between the side sheets of the tall box section and the boom foot casting.
In traditional boom foot casting/forging designs, a separately welded bulkhead plate is added to aid the boom foot in resisting twist. In addition, traditional boom foot designs feature either a separately tacked backer strip joint to the side sheet, or a machined shelf on the casting or forging for the joint to the side sheet. In these designs, a weld root exists from which a crack can originate, especially under the large axial and bending loads present at the boom foot. Traditional boom foot designs use either thicker sections or external doublers at the boom foot, to lower stresses at the weld root to prevent crack propagation.
It would be desirable to have a boom foot design that helps resist twisting at the boom foot, that eliminates the weld root at the joint between the side sheets of the tall box section of the boom and the boom foot casting, and/or that resists cracking of the welded joint between the side sheets of the tall box section of the boom and the boom foot casting.